1. Field of the Invention
The present invention relates to a method of determining a magnetic force of an electromagnetic coil in an air-fuel mixture valve which supplies an air-fuel mixture to a combustion chamber of an internal combustion engine.
2. Description of the Background Art
An air-fuel mixture valve is used to intermittently inject an air-fuel mixture to a combustion chamber of a two-cycle engine. An example of the air-fuel mixture valve is disclosed in Japanese Patent Laid-Open Publication No. Hei 5-256230, entitled "Fuel and Gas Mixing Unit". Referring to FIGS. 1 to 3 of the above publication, the gas and fuel mixing unit is an electromagnetic solenoid assembly in which the armature is moved by the magnetic force of the coil winding. The poppet valve is shifted via the armature to open a spherical valve, thereby supplying an air-fuel mixture to the combustion cylinder of the engine body. Specifically, the armature and the upper end of the poppet valve are integrally formed. The armature is moved upward by resilience of a coil spring while the coil winding remains unenergized, thereby closing the spherical valve. When the coil winding is energized, the armature is moved downward by the magnetic force of the coil winding against the resilience of the coil spring, thereby opening the spherical valve.
The foregoing electromagnetic solenoid assembly is designed so as to open the spherical valve only by the magnetic force of the coil winding when no air-fuel mixture is supplied. In other words, the assembly is designed such that predetermined valve lift can be assured when the orifice of the air-fuel mixture is at atmospheric pressure in the assembly. The assembly is inspected and then incorporated into an engine. In such an inspection, the assembly is checked to determine whether the spherical valve reliably opens and closes by energizing the coil winding when the engine body is not being supplied with an air-fuel mixture.
In order to obtain a higher output of two-cycle engines, an amount of the air-fuel mixture to be injected tends to be increased. To meet this requirement, the poppet valve has recently been enlarged, thereby increasing the valve lift, or an opening or closing stroke of the valve.
Specifically, the solenoid assembly has to double its output, which means enlargement of the coil winding. In other words, the larger the solenoid assembly, the greater power consumption. This is inevitable when the assembly is manufactured assuming that the conventional inspection method is applied.